The imperial system is a set of standards used for weights and measures. These were first outlined through the British Weights and Measures Act of 1824. Prior to using the imperial system, Winchester Standards were used beginning in the 16th century.
The imperial system is used for measurements including area, mass and volume. For length, units of measurement in the imperial system includes inches, feet, links, yards, poles, miles and leagues, just to name a few.
When measuring area, imperial units include square feet, perches, roods and acres. For volume, common measurement units include ounces, gills, pints, quarts and gallons. For mass, common units include grains, ounces, pounds, and tons.
On the flip side, there is also the metric system. The metric system uses base units such as meter (for length), liter (for volumes/liquids), and grams (for mass). A prefix is added to the base unit to indicate the exact measurement based on a decimal system, i.e. kilogram or millimeter.
If you live in the United States, you may think that the imperial system is the most commonly used throughout the world? In reality, this is incorrect. Not only is the metric system the most used system in the world, but just three countries in the world still use the imperial system of measurements.